Pippa Middleton, George Percy Aren't Dating

Not so fast. On Friday, British tabloid The Sun claimed that Pippa Middleton and college pal George Percy -- the multimillionaire future Duke of Northumberland -- had taken their friendship to the next level.

"They have always just been friends," a source close to Kate Middleton's socialite sister, 28, tells Us Weekly. "I don't know how this particular rumor got so out of control!"

Middleton and Percy, 27, have been friends since their college days at Edinburgh University, and have continued to hang out after Middleton's final split with Alex Loudon, her banker beau of two years, last fall. The Sun claimed they became romantic over New Year's, and that Percy is "completely in love with her."

"Both of them say they are friends and I've not heard or seen anything to suggest otherwise," the Pippa source adds of the pair, who've been photographed out and about in London, Spain and elsewhere with other friends.

A second source is similarly skeptical, telling Us, "I couldn't imagine them together. Their friendship is more like brother and sister."